Prior efforts in the field of single side fasteners (SSFs), and particularly expandable collet SSFs, relied upon an outer surface portion of a collet body to provide a suitable first part of a two part anti-rotation means (the second part thereof being associated with an auxiliary structure such as a housing, work piece or intermediate member, e.g., a sleeve insert, whether intrinsically or extrinsically). These anti-rotation means would prevent the collet body from rotating with respect to the auxiliary structure during rotational engagement with a screw or other rotation inducing collet expanding member while still permitting translation between the collet body and the auxiliary structure. Additionally, anti-translation means were often co-located with the collet body resident anti-rotation means. A presumed reasoning behind location of these features at or near the non-segmented body portion (proximal end) of the collet body was that maximal collet body extension would be achieved by locating the collet body anti-translation means as far from the fingers as possible, which structure was responsible for the blind side engagement aspects of the collet body.
Unless an auxiliary structure such as a work piece or sleeve insert is to be deformed in order to provide a suitable counterpart to the collet body anti-rotation means, i.e., a second part of the two part anti-rotation means, it is necessary to provide a round hole (more accurately, any portion of a round cylinder defining a bore) with some attribute that functions as a second part of an anti-rotation means. Because the prior art collet bodies relied upon anti-rotation means on an outer surface of the collet body, and preferably at a proximal end thereof, it was necessary to ensure that the second part of the anti-rotation means associated with the auxiliary structure was available during the full axial stroke of the collet body. Thus, the prior art systems and uses of the collet body relied upon affecting the characteristics of the hole through which it traversed in order to provide complementary anti-rotation structure.
Accordingly it may be desirable to have expandable collet bodies with secure anti-rotation features not relying on the through holes.